A battery anode and an electrochemical device including the same

Abstract

The invention relates to a battery negative electrode comprising a negative electrode current collector and a negative electrode active coating applied on both sides of the negative electrode current collector, characterized in that the negative electrode active coating comprises a first negative electrode active coating arranged on a main area of the negative electrode current collector and a second negative electrode active coating arranged on the edge of the main area, wherein the first negative electrode active coating has a different lithium intercalation potential than the second negative electrode active coating. The invention also relates to an electrochemical device comprising a battery negative electrode according to the invention.

Description

Technical Field

[0001] This application relates to the field of batteries, and more specifically, to a battery negative electrode and an electrochemical device including the battery negative electrode. Background Technology

[0002] In recent years, with the rapid advancement of industrial technology, various portable electronic devices such as mobile phones, laptops, and wearable devices have emerged in large numbers. Simultaneously, due to increasing human concern for the living environment, electric vehicles and various energy storage power stations have also entered a period of rapid development. These rapidly developing industries all require high-performance rechargeable batteries as energy storage devices.

[0003] Among the various existing energy storage technologies, lithium-ion batteries have been widely adopted due to their excellent energy density, long cycle life, low self-discharge, and lack of memory effect.

[0004] Lithium-ion batteries in the present technology typically consist of positive and negative electrodes coated with positive and negative active materials, a porous separator that provides electronic insulation between the positive and negative electrodes, and an organic electrolyte filling the pores of the positive and negative electrodes and the separator. In the manufacturing process of lithium-ion batteries, the positive electrode, separator, and negative electrode are sequentially wound or stacked to form an electrode assembly. This electrode assembly is then placed into a cell casing, sealed after the organic electrolyte is injected, and finally charged and formed to create a lithium-ion battery.

[0005] For such lithium-ion batteries, both the positive and negative electrode active materials are composed of materials capable of lithium-ion insertion and extraction. Common positive electrode active materials include lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium iron phosphate (LFP), and ternary materials (NCM); common negative electrode active materials include graphite, silicon-based materials such as SiOx, silicon-carbon composites, and lithium titanate (LTO).

[0006] Because graphite anodes and silicon-based anodes have extremely low lithium intercalation potentials and high theoretical specific capacities (graphite 375 mAh / g, silicon 4200 mAh / g), lithium-ion batteries with graphite or silicon-based anodes have high voltage, capacitance, and energy density, thus enabling their widespread commercial use.

[0007] However, when graphite or silicon-based materials are used as the negative electrode, lithium ions have an extremely low intercalation potential in the negative electrode (relative to the standard hydrogen electrode -3.05V) and extremely high activity of metallic lithium, which easily leads to lithium deposition and the formation of metallic lithium dendrites. These dendrites penetrate the separator and form a short circuit between the positive and negative electrodes, thus creating a great safety hazard.

[0008] To avoid the aforementioned lithium plating risk, existing technologies require various measures, such as constructing the negative electrode to have a greater width and length than the positive electrode in both the width and length directions, ensuring precise alignment between the positive and negative electrodes, ensuring that the capacity per unit area of ​​the negative electrode is greater than that of the positive electrode, and ensuring that the positive electrode active coating area never faces the negative electrode foil area.

[0009] Meanwhile, existing lithium-ion batteries are generally formed by applying a slurry to both sides of the current collector foil using a precision extrusion coating machine, followed by drying and rolling. Therefore, the areal density of the coating edge area is difficult to control, and depending on the slurry characteristics, the areal density of the coating at the edge area may be higher or lower than that in the middle. To avoid the risk of lithium plating, the electrode edges need to be cut off before use, resulting in significant waste.

[0010] In view of the above-mentioned problems existing in the prior art, there is a need in the art to develop a new type of negative electrode or lithium-ion battery to solve these problems. Summary of the Invention

[0011] To address the aforementioned problems, the present invention aims to provide a battery negative electrode, the battery negative electrode comprising a negative electrode current collector and a negative electrode active coating coated on both sides of the negative electrode current collector, characterized in that the negative electrode active coating comprises a first negative electrode active coating disposed on a main region of the negative electrode current collector and a second negative electrode active coating disposed on an edge region of the main region, wherein the first negative electrode active coating has a different lithium intercalation potential than the second negative electrode active coating.

[0012] By using the battery negative electrode provided according to the present invention, lithium deposition or lithium precipitation at the electrode edge can be avoided while maintaining a high energy density, thereby improving the safety and reliability of the electrochemical device.

[0013] In the context of this invention, the negative electrode current collector is a shape having a length, a width, and a thickness, wherein the dimensions of the "length" and "width" of the negative electrode current collector are significantly greater than the "thickness", and the dimension of the "length" is greater than or equal to the dimension of the "width".

[0014] In the context of this invention, the “main region” of the negative electrode current collector refers to the region on the negative electrode current collector defined by the length and width of the negative electrode current collector, wherein the length of the main region does not exceed the length of the negative electrode current collector, and the width of the main region does not exceed the width of the negative electrode current collector.

[0015] In the context of this invention, the “edge region” of the main body region refers to the region near the edge of the main body region in the length direction and / or the edge in the width direction.

[0016] According to one embodiment of the invention, the "edge regions" of the main body region may be distributed at the various edges of the main body region; for example, when the main body region is rectangular, the edge regions are distributed along the four sides of the main body region. According to another embodiment of the invention, the dimension of the edge regions in the length direction of the main body region is greater than 0% to 10% of the length of the main body region, for example, 1% to 10% or 1% to 5%. According to yet another embodiment of the invention, the dimension of the edge regions in the width direction of the main body region is greater than 0% to 10% of the width of the main body region, for example, 1% to 10% or 1% to 5%.

[0017] According to one embodiment of the present invention, the main body region has substantially the same length and width as the negative electrode current collector.

[0018] According to one embodiment of the present invention, a first negative electrode active coating is provided in the main body region, and a second negative electrode active coating is provided at the edge of the main body region, wherein the second negative electrode active coating at least partially surrounds the first negative electrode active coating in a plane formed by the length and width of the negative electrode current collector.

[0019] According to one embodiment of the present invention, in a plane formed by the length and width of the negative electrode current collector, the second negative electrode active coating surrounds the first negative electrode active coating only in the length direction.

[0020] According to one embodiment of the present invention, in a plane formed by the length and width of the negative electrode current collector, the second negative electrode active coating surrounds the first negative electrode active coating only in the width direction.

[0021] According to one embodiment of the present invention, the second negative electrode active coating integrally surrounds the first negative electrode active coating in a plane formed by the length and width of the negative electrode current collector.

[0022] According to one embodiment of the present invention, in the edge region, the second negative electrode active coating is directly coated on both sides of the negative electrode current collector. Alternatively, the first negative electrode active coating is directly coated on both sides of the negative electrode current collector in the edge region, and the second negative electrode active coating is coated on the surface of the first negative electrode active coating at the edge region of the main body region.

[0023] According to one embodiment of the present invention, in a plane formed by the length and width of the negative electrode current collector, the edge region may extend beyond the length of the negative electrode current collector in the length direction, and it is also possible that the edge region may extend beyond the width of the negative electrode current collector in the width direction.

[0024] According to one embodiment of the present invention, the total coating thickness in the edge region is greater than the coating thickness in the main region, or the total coating thickness in the edge region is equal to the coating thickness in the main region, or the total coating thickness in the edge region is less than the coating thickness in the main region.

[0025] According to one embodiment of the present invention, the first negative electrode active coating has a lower lithium intercalation potential than the second negative electrode active coating.

[0026] According to one embodiment of the present invention, the first negative electrode active coating comprises a first active material having a lithium intercalation potential of less than 0.5V (vs. Li / Li+).

[0027] According to one embodiment of the present invention, the second negative electrode active coating comprises more than 10% by weight, preferably 50-100% by weight, of a second active material having a lithium intercalation potential higher than 0.5V (vs. Li / Li+).

[0028] According to one embodiment of the present invention, the first active material may be a material with a lithium intercalation potential of less than 0.5V (vs. Li / Li+), such as graphite (lithium intercalation potential of about 0.1V vs. Li / Li+). + Silicon-based materials (lithium intercalation potential approximately 0.2V Vs. Li / Li) + ).

[0029] According to one embodiment of the present invention, the first negative material includes any one or a combination of two or more of the following: natural graphite, artificial graphite, graphene, carbon nanotubes, porous carbon materials, soft carbon, hard carbon; silicon-based materials such as silicon, silicon oxide SiOx; silicon-carbon composite materials; tin-based materials such as tin, tin oxide SnOx; tin-carbon composite materials; boron-based materials, etc.

[0030] According to one embodiment of the present invention, the second active material may be a material with a lithium intercalation potential higher than 0.5V (vs. Li / Li+), such as a bismuth-based material (lithium intercalation potential approximately 0.7V Vs. Li / Li+). + Phosphorus-based materials (lithium intercalation potential approximately 0.7V Vs. Li / Li) + Li₂TiSiO₅ (lithium intercalation potential approximately 0.9V Vs.Li / Li) + Li4Ti5O 12 (Lithium intercalation potential approximately 1.5 V / s. Li / Li) + LiTi2(PO4)3 (lithium intercalation potential approximately 2.5V Vs.Li / Li) + )wait.

[0031] According to one embodiment of the present invention, the second negative material comprises any one or a combination of two or more of the following: lithium titanate Li4Ti5O 12 (LTO), titanium silicates such as Li2TiSiO5, titanium phosphates such as Li3Ti2(PO4)3, niobium-based oxides such as TiNb2O7, NiNb2O7, WNb2O8, V4Nb 18 O 55 Layered sulfides, such as LiTiS2, LiVS2, phosphorus-based materials, and bismuth-based materials.

[0032] When the negative electrode uses an active material with a low lithium intercalation potential, the resulting lithium-ion battery has a high open-circuit voltage and therefore a high energy density. However, due to the low lithium intercalation potential, if lithium ions cannot be intercalated in time at the low potential, they will precipitate on the surface of the negative electrode and form lithium dendrites, thus creating a safety hazard. These safety hazards can significantly reduce the safety and reliability of lithium-ion batteries when used at low temperatures, during rapid charging, when there are defects in the capacity matching of the positive and negative electrodes, especially when the alignment between the positive and negative electrodes is not precisely controlled at the edges of the electrode sheets and the neck area of ​​the tabs, or when misalignment occurs during assembly and use.

[0033] When the negative electrode uses an active material with a high lithium intercalation potential, lithium ions are intercalated into the negative electrode active material at a higher potential. Since the deposition potential of metallic lithium is not reached, lithium-ion batteries formed with this type of active material are relatively safe, and there is no need to worry about safety issues caused by metallic lithium dendrites. However, when the negative electrode potential is high, the resulting lithium-ion batteries generally have a lower open-circuit voltage, resulting in lower energy density and limiting the battery's use.

[0034] In an embodiment of the invention, the main body region of the negative electrode still uses a negative electrode active material with a lower lithium intercalation potential, but the edge region of the main body region and the neck region of the tab use a negative electrode active material with a higher lithium intercalation potential. In this case, when the positive and negative electrodes are slightly misaligned, making the alignment not well guaranteed, or when the uniformity of the coating density at the edge of the positive electrode exceeds the acceptability of the negative electrode, in an embodiment of the invention, since the edge region of the positive electrode corresponds to the second negative electrode active coating of the negative electrode with a higher lithium intercalation potential, there is no risk of lithium deposition or lithium dendrite formation.

[0035] According to one embodiment of the present invention, the main body region of the negative electrode still has a first negative electrode active coating with a low lithium intercalation potential, enabling a higher energy density. Meanwhile, the edge regions of this main body region and the neck region of the battery tab are provided with a second negative electrode active coating with a higher lithium intercalation potential. Although contributing a lower capacity, the second active coating still has the function of lithium-ion insertion / extraction, and due to its higher lithium intercalation potential, it can prevent lithium deposition or precipitation at the electrode edges. Therefore, by means of the battery negative electrode according to the present invention, the safety and reliability of lithium-ion batteries can be improved without sacrificing battery energy density.

[0036] According to one embodiment of the present invention, the second negative electrode active coating covers at least one edge of the negative electrode current collector.

[0037] According to one embodiment of the present invention, the second negative electrode active coating covers the neck region of the tab of the negative electrode current collector.

[0038] The “tab” as used in the context of this invention exists in a manner conventional in the art, and the tab has a neck region in a manner known in the art.

[0039] The present invention also aims to provide an electrochemical device comprising a battery positive electrode, a battery negative electrode according to the present invention, and a separator disposed between the battery positive electrode and the battery negative electrode, wherein the battery positive electrode comprises a positive electrode current collector and a positive electrode active coating coated thereon, wherein the width of the positive electrode active coating does not exceed 105% of the width of the negative electrode active coating, for example, in the range of 95% to 105%, particularly in the range of 100% to 105%, and / or the length of the positive electrode active coating does not exceed 105% of the length of the negative electrode active coating, for example, in the range of 95% to 105%, particularly in the range of 100% to 105%.

[0040] According to one embodiment of the invention, in the electrochemical device according to the invention, the width of the positive electrode active coating can be substantially equal to the width of the negative electrode active coating, for example, the width of the positive electrode active coating is 95%-105% of the width of the negative electrode active coating, especially 98%-102%, preferably 99%-101%. In particular, it is conceivable that in the electrochemical device according to the invention, the width of the positive electrode active coating is 100% to 105% of the width of the negative electrode active coating, especially 100% to 102%, preferably 100% to 101%.

[0041] According to one embodiment of the present invention, in the electrochemical device according to the present invention, the length of the positive electrode active coating is equal to the length of the negative electrode active coating.

[0042] According to one embodiment of the present invention, in the electrochemical device according to the present invention, the width of the positive electrode active coating is equal to the width of the negative electrode active coating.

[0043] According to one embodiment of the invention, in the electrochemical device according to the invention, the length of the positive electrode active coating is less than the length of the negative electrode active coating, preferably the length of the positive electrode active coating is 95% to 100% of the length of the negative electrode active coating, especially 98% to 100%.

[0044] According to one embodiment of the invention, in the electrochemical device according to the invention, the width of the positive electrode active coating is smaller than the width of the negative electrode active coating, preferably the width of the positive electrode active coating is 95% to 100% of the width of the negative electrode active coating, especially 98% to 100%.

[0045] According to one embodiment of the present invention, in the electrochemical device according to the present invention, the edge region of the positive electrode active coating is opposite to the edge region of the negative electrode body region according to the present invention, so that even if the positive and negative electrodes are slightly misaligned, the direction of lithium plating can be avoided.

[0046] According to one embodiment of the present invention, the electrochemical device described herein is a battery.

[0047] Unbound by existing theories, in the battery according to the present invention, the positive electrode does not need to have a smaller size than the negative electrode in the length and width directions, and the relative positions of the positive and negative electrodes are no longer limited by the alignment in the prior art.

[0048] According to one embodiment of the invention, the battery according to the invention is formed by winding; alternatively or alternatively, the battery according to the invention is formed by stacking.

[0049] According to one embodiment of the invention, the battery is constructed in a hard-shell square or cylindrical shape.

[0050] According to one embodiment of the present invention, the battery of the present invention is constructed by means of aluminum-plastic film packaging. Brief description of the attached diagram

[0051] To make the above-mentioned objects, features, and advantages of the present invention more readily understood, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of the present invention; however, the present invention may also be practiced in other ways different from those described herein, and therefore the present invention is not limited to the specific embodiments disclosed below.

[0052] Figure 1A A schematic top view of a battery negative electrode according to an embodiment of the present invention is shown;

[0053] Figure 1B A schematic side view of a battery negative electrode according to an embodiment of the present invention is shown.

[0054] Figure 2 A schematic top view of the negative electrode of a battery according to another embodiment of the present invention is shown;

[0055] Figure 3A A schematic side view of a stacked assembly according to one embodiment of the present invention is shown;

[0056] Figure 3B Schematic illustration based on Figure 3A A three-dimensional view of the stacked assembly;

[0057] Figure 4 A schematic top view of the negative electrode of a battery according to another embodiment of the present invention is shown;

[0058] Figure 5 A perspective view of a wound battery according to one embodiment of the present invention is shown schematically.

[0059] List of reference numerals

[0060] 110 pole ear

[0061] 120 First negative electrode active coating

[0062] Second negative electrode active coating in the edge region of the 130MD direction

[0063] Second negative electrode active coating in the edge region of the 140TD direction

[0064] 150 in the neck region of the electrode, a second negative electrode active coating

[0065] Dimensions of the second negative electrode active coating in the MD direction

[0066] Dimensions of the second negative electrode active coating in the TD direction

[0067] The size of the second negative electrode active coating in the neck region of the Wn electrode ear

[0068] 160 Negative Electrode Current Collector

[0069] 210 Negative Electrode Current Collector

[0070] 220 First negative electrode active coating

[0071] Second negative electrode active coating in the 230MD direction

[0072] Second negative electrode active coating in the 240TD direction

[0073] 310 Diaphragm

[0074] 320 The negative electrode according to the present invention

[0075] 321 Negative current collector

[0076] 322 First negative electrode active coating

[0077] 323 Second negative electrode active coating

[0078] 330 Positive Electrode

[0079] 331 Positive Current Collector

[0080] 332 Positive Electrode Active Coating

[0081] 410 Negative Electrode Current Collector

[0082] 420 First negative electrode active coating

[0083] Second negative electrode active coating in the edge region in the 430MD direction

[0084] Second negative electrode active coating in the edge region in the 440TD direction

[0085] 450 electrodes

[0086] 460 insulating tape

[0087] 510 Positive Electrode

[0088] 520 diaphragm

[0089] 530 Negative Electrode

[0090] 531 First Anode Active Coating

[0091] Second negative electrode active coating in the edge region of the 532MD direction

[0092] Second negative electrode active coating in the edge region of the 533TD direction Detailed Implementation

[0093] As illustrated and illustrated in the accompanying drawings, the above and other objects, components and advantages will become apparent from the following more detailed description of specific embodiments, wherein the same reference numerals, symbols, etc., denote the same parts, components or features of the specific embodiments.

[0094] The described embodiments are some, but not all, of the embodiments in this application. The embodiments described herein are illustrative in nature and are intended to provide a basic understanding of this application. The embodiments in this application should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the technical solutions and embodiments provided in this application are within the scope of protection of this application.

[0095] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0096] The list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A or B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0097] positive electrode

[0098] According to some embodiments of the present invention, the positive electrode includes a positive current collector and a positive electrode sheet, wherein the positive electrode sheet is formed by applying a positive electrode slurry to the positive current collector in a known manner, the positive electrode slurry comprising a positive electrode active material, including but not limited to: lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese (NCM) ternary material, lithium iron phosphate (LiFePO4), or lithium manganese oxide (LiMn2O4).

[0099] According to some embodiments of the present invention, the positive electrode slurry further includes a binder and optionally includes a conductive material. The binder improves the bonding between the positive electrode active material particles and also improves the bonding between the positive electrode slurry and the current collector. In some embodiments, the binder includes: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon, etc.

[0100] According to some embodiments of the present invention, the conductive materials include, but are not limited to, carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based materials are selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based materials are selected from metal powder, metal fiber, copper, nickel, aluminum, or silver. In some embodiments, the conductive polymer is a polyphenylene derivative.

[0101] According to some embodiments of the present invention, the positive current collector includes, but is not limited to, aluminum foil.

[0102] negative electrode

[0103] According to some embodiments of the present invention, the negative electrode includes a negative electrode current collector and a negative electrode sheet, wherein the negative electrode sheet is formed by applying a negative electrode slurry onto the negative electrode current collector in a known manner. According to some embodiments of the present invention, the negative electrode of the battery according to the present invention is provided with a first negative electrode active coating and a second negative electrode active coating, the first negative electrode active coating having a lower lithium intercalation potential than the second negative electrode active coating.

[0104] According to some embodiments of the present invention, the negative electrode slurry may further include a binder, said binder comprising one or more of the following: polyvinylidene fluoride, a copolymer of polyvinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene, styrene-butadiene rubber, acrylate and epoxy resin.

[0105] According to some embodiments of the present invention, the negative electrode may further include a conductive coating located between the negative electrode sheet and the negative electrode current collector, said conductive coating comprising one or more conductive agents such as carbon fiber, Ketjen black, acetylene black, carbon nanotubes, and graphene. In some embodiments, the negative electrode current collector may include at least one of copper foil, aluminum foil, nickel foil, or carbon-based current collector.

[0106] Electrochemical device

[0107] According to some embodiments of the present invention, the electrochemical device according to the present invention includes, but is not limited to, electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and energy storage systems. To meet the high power and high energy density requirements of the lithium-ion battery in this electrochemical device, a battery pack or battery module can be used.

[0108] According to some embodiments of the present invention, the electrochemical device can be a tablet computer, mobile phone, laptop computer, etc. This electrochemical device typically requires a thin and light design and can use a lithium-ion battery as its power source.

[0109] According to some embodiments of the present invention, the electrochemical device includes a battery negative electrode according to the present invention.

[0110] Example 1

[0111] Figure 1A A negative electrode according to the invention for a stacked lithium-ion battery is shown. The negative electrode comprises a negative electrode current collector and negative electrode active coatings coated on both sides of the current collector. Here, the negative electrode active coatings include a first negative electrode active coating 120 disposed on a main region of the current collector and second negative electrode active coatings 130 and 140 disposed on edge regions of the main region. Figure 1A In the embodiment shown in the left figure, a second negative electrode active coating is arranged in the edge regions in both the MD and TD directions, while... Figure 1A In the embodiment shown in the right figure, the second negative electrode active coating is arranged only in the edge region in the MD direction.

[0112] The MD direction indicates the coating direction of the coating machine used to apply the above coating, and the TD direction indicates the direction perpendicular to the MD direction. Figure 1A In this context, the MD direction represents the length direction, and the TD direction represents the width direction.

[0113] In addition, a second negative electrode active coating 150 can be coated on the neck region of the tab, which is used to connect the negative electrode and the tab.

[0114] Figure 1A The diagram also shows the width Wm of the second negative electrode active coating in the MD direction, the width Wt of the second negative electrode active coating in the TD direction, and the width Wn of the second negative electrode active coating in the neck region of the tab. To minimize the impact on battery energy density, Wm is set to 0.1 mm to 10 mm, preferably 1 mm to 5 mm; Wt is set to 0.1 mm to 10 mm, preferably 1 mm to 5 mm; and Wn is set to 0.1 mm to 10 mm, preferably 1 mm to 5 mm.

[0115] Figure 1BThe diagram schematically illustrates a side view of a battery negative electrode according to an embodiment of the present invention. Within the scope of the invention, the second negative electrode active coating can be provided in the edge region in various ways. For example, only the first negative electrode active coating 120 can be provided in the main body region at the center of the negative electrode current collector 160, and only the second negative electrode active coating 130 can be provided in the edge region of the main body region. In this case, the second negative electrode active coating at least partially surrounds the first negative electrode active coating, as shown in embodiment 1. Alternatively or alternatively, the second negative electrode active coating can also be arranged above the first negative electrode active coating in the edge region, in which case the second negative electrode active coating covers the first negative electrode active coating in the edge region, as shown in embodiment 2. It is also conceivable that the second negative electrode active coating partially covers the first negative electrode active coating in the edge region, as shown in embodiments 1, 3, and 4. Alternatively or alternatively, the end face of the second negative electrode active coating can be flush with the end face of the negative electrode current collector as in embodiments 1 and 2, or it can also form a smooth transition shape as in embodiment 4. Furthermore, on the plane formed by the length and width of the negative electrode current collector, the edge region can extend beyond the range of the negative electrode current collector, as shown in Method 3.

[0116] Example 2

[0117] Figure 2 A schematic top view of the negative electrode of a battery according to another embodiment of the invention is shown, specifically, Figure 2 The image shows the state of the battery's negative electrode before it was cut.

[0118] In the production of the negative electrode according to the invention, multiple first negative electrode active coatings 220 are coated on the negative electrode current collector 210 along the coating direction (MD) by means of a known coating method, wherein, in the MD direction, the edges of each first negative electrode active coating are provided with a second active coating 230, thereby forming a... Figure 2 The figure below shows multiple first negative electrode active coatings.

[0119] Then, as Figure 2 As shown in the figure above, a second negative electrode active coating 240 of a certain width is coated on each first negative electrode active coating 220 at certain intervals along a direction perpendicular to the coating direction (TD) by means of gap coating.

[0120] Example 3

[0121] Figure 3AThe diagram schematically illustrates a side view of a stacked assembly according to an embodiment of the invention, wherein a plurality of positive electrodes 330, a separator 310, and a negative electrode 320 according to the invention are sequentially stacked to form the stacked assembly. The positive electrodes are obtained in a manner known in the art, comprising a positive current collector 331 and positive active coatings 332 coated on both sides thereof. Here, the negative electrode 320 according to the invention comprises a negative current collector 321 and negative active coatings 321 coated on both sides of the negative current collector. The negative active coatings consist of a first negative active coating 322 located in a main body region at the center of the electrode and a second active coating 323 located in an edge region of the main body region.

[0122] like Figure 3A As shown in the figure on the right, according to the present invention, the two outermost negative electrodes 320 of the stacked assembly can be composed of a negative electrode current collector 321 and a negative electrode active coating 321 coated on one side of the negative electrode current collector, thereby constructing negative electrode current collectors on both sides of the stacked assembly, which can further improve the energy density.

[0123] Figure 3B Schematic illustration based on Figure 3A A three-dimensional view of a stacked assembly, wherein a positive electrode, a separator, and a negative electrode are stacked sequentially to form a stacked assembly. Highly safe and reliable lithium-ion batteries can be formed through processes such as assembly, baking, electrolyte injection, sealing, and formation using techniques known in the art.

[0124] Example 4

[0125] Figure 4 A schematic top view of the negative electrode for a wound lithium battery according to the present invention is shown. The negative electrode consists of a negative electrode current collector 410 and negative electrode active coatings coated on both sides thereof. The negative electrode active coating consists of a first negative electrode active coating 420 located in the main region of the electrode sheet and a second active coating disposed around the periphery of the first negative electrode active coating. The second negative electrode active coating is arranged in an edge region 430 in the MD direction and an edge region 440 in the TD direction. The width of the second negative electrode active coating 430 arranged in the MD direction is Wm, and the width of the second active coating 440 arranged in the TD direction is Wt. A negative electrode tab 450 is also welded to the foil area of ​​the negative electrode current collector 410, and an insulating adhesive tape 460 is attached to the surface of the weld area.

[0126] The width of the second negative electrode active coating along the MD direction (coating direction) is defined as Wm, the width of the second active coating along the TD direction perpendicular to the coating direction is defined as Wt (i.e., the second negative electrode active coating at the head and tail), and the width of the second active coating in the neck region of the tab is defined as Wn. Wherein, Wm can be set to 0.1-10 mm, preferably 1-5 mm; Wt can be set to 0.1-10 mm, preferably 1-5 mm; and Wn can be set to 0.1-10 mm, preferably 1-5 mm.

[0127] Example 5

[0128] Figure 5 A perspective view of a wound battery according to an embodiment of the present invention is schematically shown, wherein the battery casing contains a core assembly formed by winding a positive electrode 510, a negative electrode 530 according to the present invention, and a separator 520. The negative electrode active coating of the negative electrode 530 according to the present invention consists of a first negative electrode active coating 531 located in a main body region at the center of the electrode sheet and second active coatings 532 and 533 disposed around the periphery of the first negative electrode active coating. The second active coating 532 is disposed along the coating direction MD in the edge region of the main body region, and the second active coating 533 is disposed along the direction perpendicular to the coating direction TD.

[0129] By providing a high lithium intercalation potential negative electrode active coating at the edge of the negative electrode, embodiments of the present invention greatly reduce the risk of lithium deposition or lithium dendrites caused by poor alignment of positive and negative electrodes, misalignment of positive and negative electrodes, or uneven surface density at the edge of the positive electrode coating.

[0130] Although various modifications have been described herein with reference to specific embodiments of the invention, it should be understood that such description is merely illustrative and should not be construed as limiting the scope of any claimed invention. Therefore, the scope and content of any claimed invention will be defined solely by the terms of the appended claims in their present form, or as amended during examination, or as implemented in any continuing application. Furthermore, it should be understood that, unless otherwise stated, features of any specific embodiment discussed herein may be combined with one or more features of any one or more embodiments otherwise discussed or considered herein. Those skilled in the art will recognize that modifications and alterations may be made to the described embodiments without departing from the spirit and scope of this application as described in the appended claims, all of which fall within the scope of this invention.

Claims

1. A battery negative electrode comprising a negative electrode current collector and a negative electrode active coating layer coated on both sides of the negative electrode current collector, characterized by, The negative active coating includes a first negative active coating disposed on a main area of the negative current collector and a second negative active coating disposed on an edge of the main area, wherein the first negative active coating contains a first active material having a lithium intercalation potential of 0.5 V lower than a lithium metal reference electrode, the second negative active coating includes a second active material having a lithium intercalation potential of 0.5 V higher than the lithium metal reference electrode, and the second active material includes any one or a combination of two or more selected from the group consisting of titanium silicate, titanium phosphate, layered sulfide, and bismuth-based material, the second negative active coating covers a neck area of a tab of the negative current collector, a coating direction of a coater used to coat the second negative active coating is denoted as an MD direction, a width Wm of the second negative active coating in the MD direction is 1 mm to 10 mm, a width Wt in a direction perpendicular to the MD direction is 1 mm to 10 mm, and a width Wn in the neck area of the tab is 0.1 mm to 10 mm, and the second negative active coating partially covers the first negative active coating in the edge area of the main area.

2. The battery anode of claim 1, wherein, The second negative active coating contains more than 10 wt% of the second active material.

3. The battery anode of claim 2, wherein, The second negative active coating contains 50-100 wt% of the second active material.

4. The battery anode according to claim 2 or 3, characterized in that, The first active material includes any one or a combination of two or more selected from the group consisting of natural graphite, artificial graphite, graphene, nanocarbon tube, silicon-based material, tin-based material, and boron-based material.

5. The battery anode of claim 2 or 3, wherein, The first active material includes soft carbon and / or hard carbon.

6. The battery anode of claim 2 or 3, wherein, The first active material includes silicon-carbon composite material.

7. The battery anode of claim 2 or 3, wherein, The first active material includes tin-carbon composite material.

8. The battery anode of claim 4, wherein, The silicon-based material is selected from silicon and / or silicon oxide SiO x .

9. The battery anode of claim 4, wherein, The tin-based material is selected from tin and / or tin oxide SnO x .

10. An electrochemical device, characterized by, The electrochemical device includes a battery positive electrode, a battery negative electrode according to any one of claims 1 to 9, and a separator disposed between the battery positive electrode and the battery negative electrode, wherein the battery positive electrode includes a positive current collector and a positive active coating coated at the positive current collector, wherein a width of the positive active coating is no more than 105% of a width of the negative active coating, and / or a length of the positive active coating is no more than 105% of a length of the negative active coating.

11. The electrochemical device of claim 10, wherein, The width of the positive active coating is 95% to 105% of the width of the negative active coating.

12. The electrochemical device of claim 11, wherein, The width of the positive active coating is 100% to 105% of the width of the negative active coating.

13. The electrochemical device of claim 10, wherein, The length of the positive active coating is 95% to 105% of the length of the negative active coating.

14. The electrochemical device of claim 13, wherein, The length of the positive active coating is 100% to 105% of the length of the negative active coating.

15. The electrochemical device according to any one of claims 10 to 11 and 13, wherein, The length and width of the positive active coating are respectively equal to or less than the length and width of the negative active coating.

Images